The present invention relates to apparatus for picking up and transferring layers of round articles and more particularly to apparatus adapted for picking up and transferring layers of round food articles or the like which are subject to surface irregularities.
Generally, the prior art has provided a large variety of transfer apparatus of the type referred to above. Such apparatus is commonly employed for handling round food articles such as fruit, particularly citrus fruit, which is subject to surface irregularities. For example, it is well known that the surfaces of the oranges are heavily textured. The oranges also include navels and may be formed with creases, both of which provide surface irregularities which may interfere with the operation of vacuum type devices for picking up and transferring the oranges.
Apparatus of the type contemplated by the present invention generally provides for the placement of fruit or other round food articles on conveyors or other means adapted to form units of fruit into layers or arrangements particularly adapted for nesting multiple layers of the fruit in packing boxes or the like. It is desirable that the units of fruit be of generally the same size and that they nest or interfit with one another in multiple layers within the case to facilitate transport of the packed fruit and also to provide a more pleasing appearance. In order to best achieve such a nested or interfitted arrangement of fruit, such machines are often adapted for placing alternating layers of different arrangements within the packing carton.
Accordingly, apparatus for picking up and transferring layers of fruit and similar articles are commonly formed with separate supply stations forming different groups of fruit, pickup heads being operated for alternately transferring these layers of fruit into a packing carton or other receptacle in order to achieve maximum nesting as referred to above.
It is also well known that mechanical handling is preferably to be minimized in order to reduce injury to the food articles. Accordingly, the use of vacuum devices for picking up and transferring such food articles has also become common. For example, vacuum transfer devices of the type generally contemplated by the present invention may be seen in U.S. Pat. No. 4,453,802 issued July 8, 1969 to F. W. Riddington and U.S. Pat. No. 3,590,551 issued July 6, 1971 to Riddington, et al., both of these patents being assigned to the assignee of the present invention. Particular attention is directed to U.S. Pat. No. 3,928,942 issued Dec. 30, 1975 to Paddock et al, also under assignment to the assignee of the present invention, since it disclosed a packing station similar to that providing a setting for the present invention. However, each of these patents is believed useful for providing a better understanding of the present invention.
It will be noted from a review of the above patents that each of them includes pickup heads with multiple vacuum cups for engaging an array or layer of round food articles and transferring them, preferably for arrangement in a packing box or the like. However, it is also to be understood that other devices have also been disclosed in the prior art which teach the use of similar vacuum apparatus for picking up and transferring generally round food products. It will of course be immediately apparent that such apparatus could also be used for other generally round fruit and vegetable products which is similarly packed in cases or boxes.
Attention is also directed toward U.S. Pat. No. 3,169,354 issued Feb. 16, 1965 to Bliss, et al, which discloses the use of similar vacuum devices for picking up and transferring eggs. The Bliss apparatus differs from the other patents referred to above in that eggs are naturally not nested or interfitted in a manner described above for citrus fruit, largely because of the very fragile nature of the eggs. However, reference to this patent makes it obvious that vacuum transfer apparatus of the type contemplated by the present invention may be useful for a variety of objects.
Generally, such vacuum type apparatus for picking up and transferring round articles such as citrus fruit have been found to perform very satisfactorily, particularly in packing stations. However, long operating experience with such devices has uncovered a number of areas where improvement appears possible. For example, as noted above, it is necessary that a complete array or layer of fruit or other objects be engaged by each pickup head and transferred properly into a carton or other container. If one or more articles of fruit is found to be missing from such a layer, it is necessary to complete the layer, usually by manually inserting additional pieces of fruit or other objects into the layer for engagement by the vacuum device. This involves stopping of the machine and results in reduced operating efficiency.
It is, of course, desirable to minimize any instances of lost fruit from the layers. However, other related problems have been found to develop in this regard. For example, where a common vacuum source is employed for engaging an array of fruit on a pickup head, the absence of one or more units of fruit in the array tends to interfere with proper development of the vacuum conditions for engagement of the other pieces of fruit. At the same time, if one or more units of fruit are missing from a layer, this is most commonly detected by different vacuum conditions in the system. It is, of course, desirable that a signal be generated as early as possible to indicate any units missing from the array so that a minimum of time is lost in completing each layer.
Other areas of improvement have also been found to exist. For example, with vacuum apparatus being employed for picking up and transferring relatively heavy objects such as citrus fruit, swinging movement of the units of fruit on the pickup heads may often interfere with proper operation of the apparatus and may even result in loss of the fruit during transfer toward a packing carton. Accordingly, it is also desirable to minimize the loss of food articles or fruit from the apparatus during transfer.
It has also been found that there is often a need for replacement or interchange of the pickup heads on the apparatus, for example, either to replace individual vacuum cups or to change the pattern of fruit in the various layers. Accordingly, there has also been found to remain a need for devices permitting more rapid replacement of the pickup heads.
When citrus fruit is being picked up and transferred, wax from the fruit tends to build up on the flexible vacuum cups, often interfering with subsequent operation. Furthermore, it is obvious that there is a need for further minimizing injury or discoloration of the fruit in order to reduce spoilage and to maintain as pleasing an appearance as possible. In addition to possible injury resulting to the fruit from engagement with the transfer device, the packing cartons or other surfaces, it has also been found that the mere use of vacuum apparatus engaging the surface of the fruit may produce a sufficient pressure differential through the skin of the fruit to result in ruptured or broken oil sacs. This condition may result in discoloration of the fruit or even increased spoilage over substantial periods of time. Accordingly, there has also been found to remain a need for improved apparatus for picking up and transferring such articles, not only to facilitate the transferring and packing of the articles but also to minimize damage to the articles themselves.